Light signal unit



NOV. 21, Q FIELD LIGHT SIGNAL UNIT Filed March 14, 1931 2 Sheets-Sheet l FIGZ.

lNvx-:No BY a /a/ ATTORNEY Nov. 2l, 1933. o, s, FlELD LIGHT SIGNAL UNIT Filed MaICh 14, 1951 2 Sheets-Sheet 2 INVENTQ? BY 4 I. du@ MMM @a ATTORN EY Patented Nov. 21, 1933 1,935,297 LIGHT SIGNAL UNIT Oscar S. Field, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application March 14, 1931.` Serial No. 522,713

3 claims.

This invention relates to light signalsfor railway signallingpurposes, and more particularly to means for focusing a lamp in such signals.

It is very necessary for light signals used in 5 railway signalling to have an efficient light projecting system as the energy consumption must besmall and the signal indication must be visible at a comparatively long range even under unfavorable light conditions. In railway signalling,

the use of reilectors or curved mirrors to increase the efficiency of a light projecting unit is objectionable because of the false indication which may be produced by an external light being reflected by the mirrors and thereby giving the appearance of a lighted signal. However, the eihciency of such units can be increased by the proper arrangement of lenses and by the proper location of the light source with respect to these lenses.

It is common practice to use incandescent electric lamps having a concentrated filament in such light projecting units and these lamps are adjusted during the assembly of the unit by the aid of a dark room or a photometric means so that the filament is in the proper focal point. However, when these light signals are in service, it is necessary from time to time to replace these lamps andthe new filament must necessarily` lament with respect to the base of the lamp and consequently the lament of a. replaced lamp rarely occupies the right focal point. An adjustment of the replaced lamp can be'accomplished by observing the appearance of the vsignal from a distance but this method is obviously awkward and very inaccurate.

In view of the above facts, it is proposed in accordance with this invention to provide alight projecting unit which permits adjustment of the lamp socket relative to the lens of the unit in such a manner that the lamp filament can be accurately located at the focal point of the lens. It is also proposed to provide means in the light projecting unit whereby the location of a correctly positioned filament is recorded to facilitate in properly adjustingk future lamp installations.

Other objects, purposes and characteristic features of the invention will appear as the description thereof progresses, during which reference will be made to the accompanying drawings, in which:-

Fig. l is a rear elevation of a proposed light (ol. 24o-44.26)

projecting unit having the rear cover and light shield removed. j

Fig. 2 is a sectional view substantially on line 2 2 of Fig. l viewed in the direction of the arrows. Y

Fig. 3 is a top view of the same unit with parts removed to show the structure of the unit.

Fig. 4 isla diagrammatical illustration of the focusing' means.

Fig. 5 is an enlarged view of an adjustable light 65 emitting plate included on the proposed signal unit. i

Fig. 6 is a perspective view on an enlarged scale, of the units, with parts broken away. Y

The particular type of railway signal employing the proposed light projecting unit is usually made up of a plurality of such units which are 'Q arranged either by position or by employing various colored lenses to produce the desired signal indications. Such signals may differ greatly in their arrangement of light projecting units according to the particular application butr all of such component units are of substantially the same construction and are interchangeable 'except for the particular colored lenses which 80 may be employed to distinguish `the indication. The light projecting unit'A illustrated consists essentially of a frame F holding an inner lens Ll and an outer lens L2 of the conventional doublet l combination. These lenses are securely held in annular rabbets in the frame F and outside of the outer lens L2 a prism deflecting glass `Ls is" similarly held which is employed to diffuse or horizontally spread the signal light to meet the particular indication needs.

A hollow backwardly extending portion F1 of the frame F carries a lamp supporting rod 1 threaded therein and locked by a nut 2 and to further prevent turning it is secured by a pin (not shown). This rod 1 is also threaded at its free 95 l end and carries a lamp socket support 3 which is retained against knurled nuts 4 and 5 by a comy pression spring 6. The support 3 receives the rod l through a-split bushing thereby permitting an angular and a vertical adjustment thereabout.`

The support 3 can then be securedin its adjusted position by a bolt 7 and nut 8 which clamps the splitbushing about'the rod 1.

A` lamp socket S is mounted in an enlarged hole in the support 3 so as to permit adjustment about a retaining screw 9 held by nuts 10 which also serves as a wire connection terminal. The socket S is held in its adjusted position by a similar screw 11 in the opposite side passing through 110' M-, or.

'translucentlsheet 23 having intersectingk cross a slot in the support 3 and held by an insulating knurled nut 12.

The socket S carries a suitable electric lamp E of the concentrated filament type which is to be located by adjusting the socket with the means previously described so that its filament or point source of light is at the focus of the lens coinbination.

The hollow frame portion F1, which is best shown in Fig. 3, has two openings 13 and 14 spaced substantially at right angles on surfaces, each facing the lamp E. A plate P, having a small center light aperture, is provided tocoverl each of these openings and emit, a small beam of light into the hollow of the frame portion FR i The plate P is shown in detail 'in' Fig. 'and contains slots at each end which fit loosely on the body of two retaining screwsl15 whicharetapped into the hollow frame portion F1 and have en,- larged heads bearing on washers 17. This permits a slight shifting of the plateA P in any directlon'on the surfaceof the hollow frame por/tion Fl andI theframe openings 13 .andili'are large enoughf not Ato interfere with the passage ofjlight through the light aperturesof the plates'P in any adjusted position.

The rearofjthe Ahollow frame portionFi holds a rear light' shieldV 19 and a cover20vv bytwo screws 21 and 22. Between these twoA 'Inernberscoverf lng the end ofthehollow frame portion F71 is a lines at each end Vthereof 'which intersect at aw point substantially in alinernent withyeachlight aperture of thevplates P and the vflament of the:

The rear light shield 19 andthe cover 2O each has two windows Wyl andV W?v whieh are Conceptric'ally located about each of the aforesaidcross Y lines of the translucent sheet 23.v4 When theunit isawaemwed @dieser Eprobeayiaed'. f and energized as previously described, the plates Pi are adjusted@ that .th W'O bafest liebt. emitted it'o" thehollow 0f, the. ,ffamepgriionslm i by Athehlight apertures thereof strikes Vthe intersection 'ofthe Icross unes' atwndowwl end fwi cilit'ateA in. making'lexternal connections lto the". "iightfprojectingunit. The rear of the unit is completelyhoused'by 'arcover C, l and a hood H of' fconv'entional 4 ldesign Ais held VYover lens v Ls i by' screws27:

Y The uit may be suitably mounted, such as by three studs 28, which are tappedfinto theframe F and held by pins 29`. rIhese sltuds`28 are shown projecting through a lsupporting back ground B spaced therefrom by springs 30 and held by nuts 3l and lock nuts 32.

It will now beseen that a light projecting unit has been provided which permits the movement of the lamp socket with respect to the/lens in practically any plane, and `which permits the socket toV be securely clamped in any such posia tion. Inasmuch as compensation for the variation in lamp filament.locations` is. necessary, a further provision has .been made to fix two points which gives a permanent alinement of the correct filament location and to fix a second two points so disposed that they aline the correct filament location along the line of the first two points.

The path of the light beams from a correctly positioned filament through the above mentioned fixed points is illustrated by the dotted lines in Fig. 4 and it can readily be seen that any deviation of the lament position in any direction will cause the light beams emitted by the plates P to strike the Windows W1 and W2 at points other than the intersection of the cross lines. In this manner, when renewing lamps, an adjustment ofgthesocket can Ybe easily and quickly made so that these light beams strike directly on the intersectionof thevcross lines at both windows and thus be assured that the intensity of the light from the new lamp'is as great as that of the old. The .above rather. specific description of one form AO fA the present invention is given solely by the way of example, and is not intended, in any manner whsvatsoever,l in a limitingsense;Y Itis also t0 bpds'ood., that? Various... mQdCaOnSfx adaptations andr alterationslmay be ,appliedtoU meettherequirements of practice, kwithout in any manner departing from the spirit or scope of the,v

prese r 1t invention, d except as A limited4 by the ap-` pended claims. Havngrthus claim -visz- A.

1.In,a light signal, ingcombinaticn, alens, a

ndescribed Amy. invention, Vwhat I light source, a support bracket fixed relatively to the lens,hadjustable socket means in the ,braclfretr V for` receiving the light source, tWQapertured plates, oversized openings in the plates, boltsV passing through ,thel openings `and into the bracket, for permittngqclamping Athe,.pla1.1S in YVarious adjusted Apositions on the bracket; the

apertures in the plates receiving the direct beams., from the light source, and two visible fixed pointi,

defining vmeans on. the bracket for respectively directly 4receiving light, beams passing through said apertures, whenthe light sourceis on focus.v

2. In a light signal unit,a frame member,a

lens carriedby the member, said member hav; ingY a hollow rearwardly extendingY portion open ing at the rear and VVhavingtwo windowsV therein,

, at `the rear, an opaque member covering the open@ point defining means on the windows,.two plates,

means for securing the plates .to said hollowframe 125 f1 portion and including loosely fitting screws pass: ing through apertures in the plates, a perforation in eachplate, holes in said hollow frameportion,

covered by, said plates, vsaid plateswhen in adr: justed position Yallowing the passage of two radial n,

light beams from the light Source atthe ,lens focus-upon said point defining means.

3. kIn, aligl:it Vsignal unit, a frame membena lens in the frame member, a light source support onlthe frame member, said frame member having a hollow rearwardlyextendingportion, two,.- spaced translucent screens in the hollowportion,

pointidentifying means onlthe screens, two aperturedplates, and means for iiXingthe plates inV 

